Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description takes on the burden of explaining behavior. It clearly states that the tool lists both user-uploaded and server-generated files, and includes sizes, which is sufficient to infer a read-only, non-destructive operation. It does not mention any side effects, but none are expected.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, concise sentence that conveys all essential information without redundancy. It is front-loaded with the action and subject, making it easy to parse.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple listing tool with no parameters, the description is complete. It explains what is listed, for whom, and what information is included (sizes). Given the lack of an output schema, this adequately covers the expected return value.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool has zero parameters, and the schema reflects that (100% coverage). The description adds no parameter-specific detail, but none is needed. The baseline for no parameters is 4, and the description does not introduce ambiguity.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose with a specific verb ('List') and resource ('PDFs stored for your token'). It also distinguishes itself by mentioning both uploaded and server-generated files, making it unambiguous among the sibling tools.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description effectively indicates when to use the tool (to list all stored PDFs) and implicitly conveys that it is the appropriate choice for a full inventory. It does not explicitly name alternative tools, but the contrast with count/info tools is inferable from the listing scope.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.